Tilting mechanism for chairs



W. F. HEROLD 4TILTING MECHANISM FOB CHAIRS July 2o, 1937.

2 Sheets-Sheet 2 Filed May 16, 1935` 25 increased duringtilting.

Patented July 20, 1937 aosvasif 'rnfrrno MECHANISM ron CHAIRS Walter Heroianriageport, oenn.,as`signor"to ,The `Bassick Company,` Bridgeliort," Connu a corporation of Connecticut Application May 16,21935, Serial No. `21,739

i. y y y l Utontons. (oi. 155-175 l .A The present invention relates tovtilting mechlanism for chairs, either of the type in which thefchair seat is tiltable relatively to a support ing base, or in which' the chair backis tiltable relatively to the chair seat,and is -an improvement over the chair irondisclo'sedin my copending application S. N. 695,989 ledOctober 31, 1933, Patent No. 2,008,209 issued July 16,v 1935 sponding parts throughout the several figures of and in whichthe tilting action't'akes place in a hinge iointof` rubber orother suitable material,` the rubber being in the formof a cylinder disposed under permanent pressure and tension between inner and louter, co-axial concentric members to which therubber isin effect bonded, the relative movement 1 b`etwee'n"th`ese "members being supported by the torsionalvstrain s'et upin the compressed rubber.j

According to the invention disclosedin said` y application the rubber is under a predetermined initial tension yieldingly holding' the tiltable `member in its norr'nal"non-tilted` position, "and as the tiltable member istiltedtheftension `and resistance inthe rubber' is ybuilt up tosupport 4theincreased load as .the"pres`sure moment is It is proposed in thexpresent invention to provide means whereby theangularity of movement vof the `joint elements willbe inicreased ratio to the angularityof movement ofthetilting member, andllconseqently the tensiongset l up inV the rubber will be of a different order than is thefcas'e `wherethe angularity of `move- `ment"of`tlie` jointelements corresponds tothat of the tilting membento the `endit'hat the proper angularityA of "movement to lproduce "the desired tension in theM rubber may" be produced "independently of the particular angularity of movementof the tilting rnern'berlA With the above and othefobiects inview em- 40 bodiments" of my invention are shown in 'the i accompanying drawings, and these embodiments will "be hereinafter moref'fully described with reference thereto, and the invention will be finally kpointed out nthe claims.4 s

In'thedrawings 'i ,l Fig. 1 is aiV side elevationf'of a :chair ironembodying the invention, the forward and" rearward tends of the seat `supporting `spider arms Vmissing broken away. w

Fig. 2 isa top plan vieW, a'`-`portion of `one of the spider arms being broken lavvayi `Fig`3 isa vertical sectional` view, taken'along 'theline3--3'o-Fig; 1. Figa 4 is ai side elevation `of a modiedform Wwardly projecting flat-surfaced formed upon theupper sides, and against which 40 the upper portions ofvthespider armslU-I `rest vinthe normal non-tilted position `oi the `chair seat." IThe upper surface ofthe bracket A Il `is"inclin`ed 'rearwardly and downwardlypas at 2|, tangentiallyto the tilting arcof the spider 45 "arms to form a limit stop to the rearward tiltling action'i ofthe chair seat, as indicated by the l dot-and-'dash linesFig; 1.

of chairiron,.according to the invention,` adapted fortiltably supporting a chair back.

i Fig. 5 is aplan view thereof `with the seat removed and withcertain parts broken away and insection. i z 5 `lig. 6 is. a vertical sectional view, vtaken along the line E-6 of Fig. 4,;,the seat being removed.

Similar reference characters indicate correthe drawings. i i 10 t Referring to the drawings and moreparticularly to Figs. 1 to 3 `thereof,. the chair iron, according to the illustrated exemplary embodi- 'ment of the invention, comprises -a pair of angular cross-section spider arms `lll--Hliadapted 15 to be` screwed to the underside of the chai` seat in the usual manneiyand mounted `for tilting tended through a transverse tubularbushing I5 inv the bracket `I|, the shaft having reduced 2,

threaded extensions lB-Ifi at itSJendsJengaged y `through apertures llll in the ,spider arms, and having nuts I8-l8 screwed thereon which rigidly `connect the shaft to the spider arms, this `shaft providing'afsupporting spacer or strut be- 30' tween the arms.4 Thetbearingt bushing l5 is f preferablyl formed of yrubber, `graphite impregnated bronze' 'or other suitable type `of oil-less l and noiseless bearing material.

The bracket l|-is provided in forwardly spaced relation tothe tilting axis of the shaft-M ,with

a 4pair of forwardly projectingitransversely spaced cylindrical bearing" portions l9|9, having uplugs i 20-20 tubular member 23, and acylindricallbody of rubber 24 between them, this rubber body being highly 4compressed and confined between the 55 y under compression.

rubber is thus highly compressed and. is in effect bonded to the inner surface of the member 22 by the great surface friction set upbetween them 'Ihe ends vof the inner"tub,ular member 23 project beyond the rubber member 24, as well as beyond the outer tubular member'22, and are provided with grooves 25-25, which are adapted to be interlockingly engaged with ribs 26-26 formedupon pinion gears 21-21, iand which t gears arerigidly connected to said inneratubular A member by means of a tie-bolt 28,headedat one end Vand screw. threaded at the other end, a nut 29 being engaged upon said screw threaded end;

' :To'the inner surfaces of the sides of= the spider arms Ill-I0 there, are-secured a pair of segment 1 gear members 311-30, the teeth `of which` are A vconcentric to the tilting axis of -the chair seat,

and'which mesh with the pinionvgears 2 1-213 Withintthe space between the bearing portions |9-I9 a tension applying an adjustment lever 3| is. disposed, ,its collar portion 32 being engaged about the intermediate portion of the outer joint member; 21am; being secured-thereto by a set `screvvl33..gAn adjusting yscrew 34 having a hand wheel or nut 35 at its end is engaged in a threaded ropening36 in the end of the ylever l3land is adapted to bear at its innerr end uponan abutment portion 31 formed upon the Vbracket I-l. It .will'beobvious that by adjusting--therscrew 34 the outer tension element member 22 is rotated with respect to'the inner-tension element memfber 23; .thelatter being held `against rotation through the engagement of the pinions 21 with the segmentalv gear members .30 of the spider arms and through the engagement of the spider tarms with thestop. lugs 2U- 20.

A torsional strain is thus set up `in thev rubber producing .an initial tension in ,the latterv which exertsA pressure tok move thel chairrseat in counterclockwise direction yand thereby-retain it in its .normal non-tilted position, the greater the initial tension the more force yrequired to ltiltthe chair lseat rearwardly from its-non-tilted'position. As

the chair seat is tilted rearwardly `,the gear segments 30 rotatethe innertension-element member 23 through an angular movementhaving. an increased ratio ,over thev angularI ,tilting `movef ment Aofthe chair seat, and thus tension `is-,built upinethe. rubberA which increases indirect proportion to t s ratio as lthe chair seatis tilted rearwardly, t us providing adequate-supportfor the increased load. as the weight is shifted rearl1 wardly.. The build-up of the` pressure in the :rubber element as the seat is tilted should, under *normal conditions, be such as to compensate for the additional weightl or pressure moment imf posed as the tilting isincreased, in other words,

the 'increase of tensionA should be proportionate to the increase of vthe pressure rmoment,l and therefore approximatestable equilibrium at any point of tilt' will result. t In Figs. 4a'nd'5` I have shown amodied form in which vthe invention is embodied in a tilting y'back for a chair, as for instance a' posture chair.

A bracket 40 is secured, asby rivets 4|, near the rearward ends of the spider arms Ill- 40, and is provided with a pair'of spaced cylindrical bearing portions 42--42 in which the tension element, comprising the outer and inner cylindrical tubular elements- 22 and 23 'and the intermediate rubbery element 24, is disposed, the inner element vliaving-the pinion gears l21-21 rigidly secured to its -ends by means 4 0f vthe Atie-bolt 28.

` A tilting frame member comprising a rearward chairback supporting portion l43 and side portions 44-44 is tiltably mounted upon the rearward ends of.v the spider arms by means of pins 45-45 engaging bearing portions 46-46 formed upon the side portions 4444. segmental gears 41-41are secured upon the forward ends of the sideportions44--44 and mesh with the pinion gears 21-21 of the tension element,y the tilting member being limited in its non-tilted position by abutmentof the'lower endsof the segmental gears 4'1-41 with stop lugs 48-48 provided on the bearing portions 42v and being limited-in its tilted position by engagement-of the upper surfaces of the ,side portions.4444 with jinclined abutment lsurfaces 434-49 provided upon the bracketf40.

vWithin the-space'between the cylindrical bearing portions 42-42 a tension adjustment lever 4 50 is disposed and projects rearwardly, the collar portion 5I of the lever being Vengaged about the y intermediate portion of the outer tension element member 22 and secured thereto by a. setscrew 52. An adjusting screw 53 having a hand- -wheel'or nut'v 54 at its end isengaged in a threaded opening 55 in the end of theI lever 50 and is adapted to bear at its upper end` upon the under surface yof an abutment lug -56 formed upon the bracket Il. y

.The chair back vis mounted for vvvertical and angular adjustment relatively 4to the tilting frame member, and for thispurpose the rearward portion 43 of the tilting frame member, which pro- J'ects for a considerable distance below-the side portion 44-44, is provided with a. vertically disposed recess 51 in which is engaged the vertically portion 51 and engaged by a. bolt 6I extending through an aperture 62 inthe bracket member 59, a handlwheel or nut 63 being screwed upon the end of the rbolt which normally secures the bracket member 59 in its adjusted'position on lthe portion 43, but upon being loosened' permits vertical adjustment for the .purposeof raising or lowering the height of the chair back.

A pair of. ear lugs 64'64 are provided at the upper end of the bracket rmember 59 to which a pair of ear lugs 65-65 formed on the chair back frame member 66 are pivotally connected by pins 61-61.

Centrally of the frame member 56' and below the lugs 65-65 there are provided ay pair of ears 68-:68 to which a block-member 69 is pivotally connected'by means of a pin 1li,v this blockmember being provided in its forward face with an VVinclin'edT-slot 1I in which is engaged an lnclined` T-rib 12 provided upon a. linkblock memvber 13, thisv member 13 having a, threaded pasvchair back with respect tothe member 59 the screw shaft 11 is turned in one direction or the 76 other whereupon the link-block` member '13 is shifted transversely in one direction or the other, and through its inclined T-rib and slot connection with the block member 69 swings the lower end. of the chair back frame member about the pivots Sla-61 either toward or awayfrom the member 59.

The operation is substantially similar to that of the first embodiment, except that, instead of the seat tilting about thel supporting base theV chair back, supported by the bracket 59 and tilting frame member, tilts relatively to the chair seat and bracket `42 upon rearward pressure being applied against the back by the person seated in the chair, the segmental gears 41-41 being swungto rotate the inner tension element member 23 through theV pinion gears `21`21 to apply gradually increasing tension in the rubber body 24 of tension tothe element. l I

I have illustrated and described preferred and satisfactory embodiments of myinvention, but it `will be obvious that changes may be made theretween said' joint elements, means rigidly bonnecting one of said joint elements to said Isupporting member. a gear rigidly connected to said other joint element and a. gear carried by tiltable member and meshing with said rst mentioned gear whereby upon tilting of said tiltable member there is relative rotary movement between said joint elementsto tension said tension elet ment, stop means on and cooperating between said supporting member and said tilting member forl limiting the movement of said tilting member in one direction, one of said joint elements being disposed in a state of initial rotation relatively to the other joint element to produce initial tension in a direction to normally force said tilting member in said one direction.

2. In a tilting mechanism, a supporting mem--V ber and a member tiltable relatively'to said supporting member, resilientjoint means carried by said supporting member comprising a pair of joint elements and a tension element acting bei tween said joint elements consisting of an annu--` lar body of rubber compressed and conned between said jointv elements andbonded thereto, means rigidly connecting one of said joint elements to one of said membersa gear rigidly c'onnected to said other joint element and a. gear carried by said other member and meshing with said rstkmentioned gear, whereby upon tilting of said tiltable member there is a relative rotary movement between said joint elements to tension said tension element, stop means on and cooperating between said supporting member and said tilting member for limiting the movement of said tilting member in one direction, one of said joint elements being disposed in a state of initial rotation relatively to the other element to proi duce initial tension in adirection `to normally force said tiltingmember in said one direction.

WALTER F. HEROLD. 

